The present invention relates to a small lightweight portable computer called a mobile terminal, and an information providing method and system in which an information server provides the mobile terminal with appropriate service information which the mobile terminal desires and which is related or strongly correlated to an area where the mobile terminal is present, depending on the position of the mobile terminal.
The invention which provides the user of a mobile terminal with very convenient meticulous services by using information on the position of the terminal is disclosed in JP-A-5-102906, entitled "Mobile Communication System". In this invention, the user who is able to know his position, using a car navigation system, sends information on the user's position through a car telephone to a service center and downloads the newest information on a possible traffic jam and/or a map concerning his position from the service center. Another invention discloses that without receiving information on the user's position expressly from the user, an area in which the user is present is presumed on the basis of a position of a base station for car telephones, and service information on a possible traffic jam, etc., in that area is downloaded.
In the above conventional techniques, when the newest map data is to be obtained to know the newest route situation on route interruption due to road works and/or opening of a new route, the data transmission rate through the car telephone is low, for example 2.4 kbps whereas compressed map data still reaches several tens of kilobytes or more. Thus, the car travels about several kilometers during only the time taken for sending the retrieved map data and necessary information can not be obtained on a real time basis. Actually, radio transmission by the car telephone provides low quality data and a bit error is likely to occur. For ensuring purposes, re-transmission of data is required and hence it is difficult to receive necessary information on a real time basis.
In the above conventional inventions, for example, information on the occurrence of a traffic jam over a specified length of a specified road in a specified area in the vicinity of user's position is given to user in response to the user's inquiry. Thus, unless the user has a knowledge about a route in which a traffic jam is likely to occur, the user does not know the timing in which the user inquires about such information, would be involved in the traffic jam, and wishes to obtain information as to how many hours it would take from the occurrence of the traffic jam to its disappearance. However, the user should rather know which route the user should select to reach his destination in a minimum time when a traffic jam occurs on his selected route than he knows how much time it would take from the implication of the user into the traffic jam to the clearance of the jam.